Engine starter



May 13, 1941. J, w, Frrz GERALD 2,241,639

' ENGINE STARTER y Filed Feb.' 20, 1959 nnlllll-Illll Patented May 13, 1941 ENGINE STARTER John W. Fitz Gerald, Milwaukee, Wis., assignor to Briggs & Stratton Corporation, Milwaukee, Wis., a corporation of Delaware Application February 20, 1939, Serial No. 257,438

(Cl. 'i4-7) Claims.

This invention relates to engine starters of the type illustrated in .the Reissue Patent No. 20,686, issued to John W. -Fitz Gerald, April 5, 1938.

Engine starters of this type are characterized by the fact that the necessary resiliency in the drive between the power shaft and the pinion propelling means is obtained through use of an elastic body which resiliently transmits rotation through frictional engagement thereof with the driving and driven elements. This el-astic body is preferably in the form of a rubber ring and in starters of this type, heretofore in use, the rubber ring was compressed endwise between suitable abutments on the driving and driven elements.

The provision of the necessary frictional grip to carry the load for whi-ch the starter is designed, requires a certain minimum area of engagement between the rubber ring or other elastic friction mem-ber and its cooperating elements; and as past .constructions required both the bore and .the outer circumference of the friction member to be spaced from adjacent surfaces, ,the attainment of the required area of contact entailed an increase in the diameter of the unit.

The present invention has, as one of its objects, to provide an engine starter of the character described wherein the frictional driving en gagemend; between the elastic member and its cooperating elements is not limited to the ends of the resilient member so that the over-all diameter of the unit can be safely reduced.

Another object of this invention is to provide an impro-ved manner of resiliently transmitting driving force from the power shait on the starter to the pinion propelling or actuating member which simplifies lthe design and reduces manu faoturing costs.

With the above and other objects in View which will appear las the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly dened by the appended claims, it being underthrough an engine starter constructed in accordance with this invention and 'showing the pinion retracted;

Figure 2 is a view similar to Figure 1, but illustrating the .parts in the positions which they ocv cupy at the time the load of the engine is picked erally by ythe numeral 'l meshes during the startstood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within thev scope of the claims.

The accompanying drawing illustrates two complete examples of the physical embodiment of the invention constructed in accordance with the best modes so far devised for lthe practical application of the principles thereof, and in which:

Figure 1 is a longitudinal sectional view ing action.

The start-er, as is custom-ary, is mounted on lthe armature shaft 8 of the starter motor 9 and is so arranged that upon initial operation of the starting motor, the pinion E is propelled forwardly into mesh with the ring gear and upon starting of the engine the overrunning action of the pinion causes its retraction out of mesh with the ringgear.

Although the pinion 6 is mounted to slide along ythe shaft 8, it is actually Carried by a pinion actuator I0 in the `form of a screw and with which an `extended hub Il on the pinion has a threaded engagement. The screw or pinion actuator l is freely slidable and rotatable on .the shaft 8 and is drivingly connected with the shaft through a resilient or flexible coupling indicated generally 'by the numeral l2.

IIlhis coupling, as in the aforementioned patent to John W. Fitz Gerald, Reissue No. 20,686, incorporates an annular body of elastic material I3 having a high coefficient lof friction, 'such as rubber and maintained in a state of compression to have a frictional driving connection with the pinion actuator and the shait in a manner now about to be described.

The shaft 8 has a collar i4 secured thereto by means of a set screw l5, and extending radially from Ithis collar is a flange I 6. The face of this fiange irictionally engages the ladjacent side wall ofthe rubber ring |13 .f

A somewhat similar frictional driving connection is established between the rubber ring and the pinion actuator but in a manner permitting a reduction in over-all diameter withou-t sacricing area of contact. Tothis end, the bore of the Y rubber ring hugs the outer cylindrical surface of an unthreaded hub extension or sleeve I1 on the pinion actuator.

The fric-tional driving connection between Ithe rubber ring and the pinion actuator is thus at the center of the ring and has as its area the entire surface of the bore in .the rubber ring.

The rubber ring is maintained in a state of compression by `a Washer I8 loosely mounted on the unthreaded portion II o-f the pinion actuator and drawn toward .the iiange I6 by an outer shell or `cover I9, the ymarginal edges of which are turned over the peripheral portions of the washer and iiange.

It is to be observed that the unthreaded portion I1 of the pinion actuator extends through the entire thickness of .the rubber ring when the starter is in its normal unloaded condition and the rubber lring is compressed an extent sumcient to merely provide initial driving force.

During operation of the starter and upon forward propulsion of the pinion into mesh with the ring gear, the application `of the engine load onto the starter effects further compression of the rubber ring by virtue of the fact that forward movement of the pinion is obstructed by a stop 2t. During this period, the relative endwise motion between the pinion and its actuator is yieldingly opposed by the rubber ring inasmuch as the washer I8 abuts the adjacent ends of the threads on the actuator.

The extent to which the rubber ring can be compressed during this action is limited by the engagement of the outer end of the unthreaded portion I? of the pinion actuator with the bottom of a counterbore 2| in the collar I4, as clearly shown in Figure 2.

In the construction illustrated in Figure 3', the outside as well as the inside cylindrical surface of the rubber ring is employed. for the transmission of driving force. To this end, the washer or flange I8' is Xed toI the pinion actuator iii. Any suitable manner of securing these parts together may be employed. They may be welded together, or, if desired, the actuator and the flange may be cast or forged as an integral unit.

In addition, the shell I9 is secured to the flange IIE of the collar or abutment I`4 so that it turns with the shaft.

With this construction, the outer cylindrical surface of the rubber ring and its end which engages th-e flange IE are frictionally connected with the shaft, While the inner cylindrical surface or bore of the ring and its opposite end are frictionally engaged with the pinion actuator. The area of the driving surfaces of the rubber ring is thus approximately doubled for a given volume of rubber.

From the foregoing description taken in connection with the accompanying drawing, it will be readily apparent to those skilled in the art that this invention simplifies the construction of starters of this character, and that it permits -a reduction in over-all diameter without sacrificing area of f-rictional contact between the rubber ring and the pinion actuator.

What I claim as my invention is:

1. In an engine starter ofl the character described: a power shaft; an abutment Xed on the shaft; a pinion actuator on the shaft freely movable thereon and having a'sleeve portion at all times adjacent to said abutment; a pinion; a threaded connection between the pinion and its actuator; a rubber ring tightly embracing the sleeve portion of the actua-tor and frictionally engaging the abutment; a washer loosely encircling said sleeve portion and engaging the side of the rubber ring opposite its side which engages the abutment; and means for holding said washer and abutment together to compress the rubber ring therebetween and maintain frictional contact between the bore of the rubber ring and said sleeve portion and between the abutment vand the adjacent side of the ring.

2. In an engine starter of the character described: a power shaft; an abutment secured to the shaft and having a surface substantially angular thereto; a pinion actuator on the shaft freely movable thereon, said actuator having a threaded portion and an unthreaded sleeve portion, the sleeve portion being adjacent to said abutment; a pinion having a threaded connection with the threaded portion of the actuator; an annular friction member of elastic material gripping the sleeve portion of the pinion actuator and having one side thereof in frictional engagement with said angular surface of the abutment; a washer loosely mounted on said sleeve portion With one side -in engagement with the adjacent portion of the annular friction member and its other side engageable with the adjacent end of the threaded portion of the pinion actuator so that movement of the pinion actuator toward the abutment effects compression of. the annular friction member and an increased frictional engagement between it and said sleeve portion and abutment; and means for holding said washer and the abutment against separation beyond a predetermined distance at which said annular friction member is in a degree of compression.

3. In an engine starter: a power shaft; a pinion propelling member freely movable on the power shaft and a resilient driving connection between the shaft and said pinion propelling member comprising a sleeve fixed with respect to the pinion propelling member; an abutment fixed on the shaft and having a surface angular to the shaft; a rubber ring mounted on said sleeve with its bore gripping the sleeve and one side frictionally engaging said surface of the abutment; means for maintaining the rubber ring in an initial state of compression for transmitting rotation from the shaft to the pinion propelling member; means for increasing the compression of the rubber ring as the starter picks up the load of the engine; and means for limiting the compression of the rubber ring.

4. In an engine starter: a power shaft; a pinion propelling member freely movable on the power shaft and a resilient driving connection between the shaft and said pinion propelling member comprising a sleeve fixed with respect to the pinion propelling member; an abutment fixed on the shaft and having a surface angular to the shaft; a rubber ring mounted on said sleeve with its bore gripping the sleeve and one side frictionally engaging said surface of the abutment; means for maintaining the rubberY ring in Van initial state of compression for transmitting rotation from the shaft to the pinion propelling member; and means for increasing the compression of the rubber ring as the starter picks up the load of the engine, said sleeve having its end adjacent to the angular surface of the abutment when the rubber ring is in its initial state of compression and said abutmentV having a counterbore to receive the end of the sleeve as compression of the rubber ring progresses, the bottom of the counterbore providing a stop against which the end of the proximity thereto, said angularly disposed surfaces cooperating with each other to at all times form a completely closed annular chamber; and a rubber ring encased in said annular chamber and frictionally engaging at least both of said angularly disposed surfaces on the pinion actuator and one of said angularly disposed surfaces on the abutment to provide a driving connection from the abutment to the 10 pinion actuator.

JOHN W. FITZ GERALD. 

